reached a given size, there are few benefits to be gained by increasing density. A city of 7 million cannot improve its park facilities, theaters, selection of concerts and art galleries, or its traffic arteries by increasing its population. Furthermore, given the opportunity to maintain an income, millions of Americans have shown their preferences for low-density areas by moving from the inner city to the suburbs. The tendency of industries and, therefore, of populations to concentrate raises some fundamental issues of public policy. In the developed areas of the world these tendencies have led to the growth of densely populated urban centers and to the depopulation of rural areas. In the developing areas of the world it also is resulting in increased regional disparities. Both in the developed and in the developing world we must ask whether it is possible to achieve a more even distribution of industry and, therefore, of populations without losing the benefits of modern technology. As population densities increase in the decades ahead, we may very well see governments developing not only family planning policies but population distribution policies as well.* Population Size and Size of Government. The relation between population size and the optimal size of a government is a question which has occupied the attention of political scientists and social theorists since the time of the Greeks. Until modern times, the concern was very much with the question of what constituted an optimal unit for democratic government, and the answer for centuries was that it should be small enough to permit direct participation. How democracies could function within units larger than city states—in large republics—became an important issue among British and American political theorists in the late 18th and early 19th centuries. Thus there developed the concepts of factions, parties, and representation as ways of linking the citizen to the state in a large republic. More recently, as economic values have grown in importance, there has been a concern with the relationship between the size of government and the cost of government as they are related to the specific functions performed by government. The concept of "economies of scale" has increasingly been applied to considerations of government size. This concept assumes that there are certain "indivisibilities"—that is, there are minimum costs for certain activities irrespective of the numbers of people involved. Thus the costs of a highway of a given size are more or less the same whether the highway is used by a few automobiles or very many. And the costs per unit for electricity or for water are often lower for larger settlements than for small towns. The economies-of-scale argument often leads one to stress the economic advantages of larger units of *For an excellent statement on the need for a population distribution policy for the United States, see (46).ntages of urban living. But even in this debate the most enthusiastic supporters of cities must admit that once a city ha are primary, and local resources and population density arc relatively less important.